There are a variety of light-emitting devices, such as light-emitting diodes (LEDs), laser diodes, and optical amplifiers, which can emit light and which may be used in various applications. The emitted light may be characterized by numerous metrics, including light extraction, collimation, and azimuthal isotropy. Light extraction is a measure of the amount of light emitted as compared to the amount of light generated within the light-emitting device. Collimation is a measure of the angular deviation of emitted light with respect to the normal of the emission surface of the light-emitting device. Azimuthal isotropy (or uniformity) is a measure of the uniformity of light emitted versus an azimuthal angle, hereafter sometimes referred to simply as isotropy.
Each of the above-mentioned metrics of a light-emitting device may play an important role in determining the suitability of a particular light-emitting device for different applications. In general, light extraction relates to device efficiency, since any light generated by the device which is not extracted can result in decreased efficiency. Light collimation can be of importance if an application that incorporates the light-emitting device operates more efficiently, and/or with fewer optical components, as a result of the collimated light emission. Azimuthal isotropy may be of significance in applications where isotropic light emission is desired, and where isotropic light emission may reduce or eliminate the need for additional optical components.
As such, in many applications, it can be desirable to tailor light extraction, collimation, and/or azimuthal isotropy.